McCain warned during an acceptance speech for the Liberty Medal that choosing to “refuse the obligations of international leadership … for the sake of some half-baked, spurious nationalism cooked up by people who would rather find scapegoats than solve problems” is unpatriotic.

“As unpatriotic as an attachment to any other tired dogma of the past that Americans consigned to the ash heap of history,” he continued. “We will not thrive in a world where our leadership and ideals are absent. We wouldn’t deserve to.”

The president responded to that criticism during an interview on Chris Plante’s radio show.

“People have to be careful because, at some point, I fight back,” Trump said.